1. Field of the Invention
The present invention relates to a gas supply apparatus for the manufacturing of a semiconductor, and more particularly to a gas supply apparatus for a semiconductor manufacturing apparatus, which enables downsizing of the gas supply apparatus and reduction in the production cost of the apparatus.
2. Description of the Background Art
In the manufacturing of semiconductors, it is common practice to use a wide variety of gases in a switching manner or use the same type of gases in parallel at different flow rates. Therefore, in a conventional gas supply apparatus for a semiconductor manufacturing apparatus, a flow controller such as a mass flow controller is provided for each of gas systems, to which gases are to be supplied, so as to control the flow rates of the supply gases with high accuracy.
For example, an etching process, one of the main processes in the manufacturing of a semiconductor, is generally carried out in multiple steps in which a plurality of insulating films are etched sequentially. In each etching step, etching is carried out by using three or four types of gases in combination. Accordingly, a total of at least ten types of gases and flow controllers are needed only for a gas supply apparatus for the etching process. A huge number of flow controllers are necessary for the entire semiconductor manufacturing facility.
In the case of a CVD process, the process is sometimes carried out by simultaneously supplying the same type of gases from a plurality of supply ports into a processing reactor at the same or different flow rates. A flow controller is generally provided in a line connecting with each supply port to control the flow rate of the supply gas. Thus, a large number of flow controllers are needed in total.
While mass flow controllers have most commonly been used thus far, pressure type flow controllers have been developed in recent years. However, when a large number of flow controllers are installed in a gas supply apparatus as described above, the gas supply apparatus should necessarily be large-sized one and involve high costs for its production and maintenance. Furthermore, the installation of a large number of flow controllers makes the maintenance of the flow controllers troublesome and time-consuming and, in addition, necessitates a large number of replacement parts and spare parts, thus incurring high running cost for the gas supply apparatus.